The federal bureaucracy's spending on consultant managers and business professionals is increasing by almost $1 billion every year as documents show they can be paid four times more than full-time public servants doing the same job.
Internal Defence Department paperwork shows it has looked at paying a chief engineer up to $660,000 a year - or $3000 a day - when a bureaucrat doing the same job would receive $160,000 annually or less.
The consultant has already been employed but Defence did not comment when asked to confirm whether the outsourced expert was paid this amount.
If the large pay packet was signed off on the chief engineer overseeing Defence's stored fuel would receive almost as much as some department and agency bosses.
The proposed cost of the consultant was outlined in a Deloitte report prepared to help Defence set up a new fuel services branch as the department deals with major problems in its fuel supply chain.
A public servant doing the job would be ranked executive level 2.2 and receive $130,000 to $160,000.
Defence has encountered difficulties managing vast quantities of fuel, and other consultants costed to work with Defence's fuel were costed at $1500 and $2000 a day.
The Wraith Review, which is yet to be made public, was expected to have outlined all the problems involved.
In December, Defence put out tenders worth up to $10 million dollars to fix potentially dangerous fuel stations in Sydney two years after problems at depots across Australia were identified, including issues with electrical earthing or bonding, fading safety signs, non-compliant electrical equipment, non-compliant testing laboratories and vital retaining walls in poor condition.
Professionals Australia ACT director David Smith, whose organisation represents engineers and technical staff in the public service, has questioned the need for an expensive consultant to be used to oversee the fuel storages, particularly because a long-term staff member would retain corporate knowledge.
"The contractor that they have employed has civil engineering qualifications but not chemical engineering qualifications," Mr Smith said.
"Both are probably important in the branch.
"They could have had two ongoing EL2s for a salary cost of $260,000 to $290,000 a year and had one civil engineer and one chemical engineer. Why wouldn't you want to ensure your key oversight staff were kept in-house," Mr Smith said.
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A Defence spokesman said some limited technical expertise had been contracted on a short-term basis.
"As the Fuel Services Branch matures, it is intended that all ongoing staffing requirements will be primarily met through the use of ADF and APS resources," the Defence spokesman said.
A report leaked in November showed Defence had a huge shortfall in engineers and technical staff.
The public service spent $11.1 billion on consultants in 2014 compared to $9.1 billion in 2012, $7.2 billion in 2010 and $5.3 billion in 2007, according to Austender figures focusing on managers, business professionals and administrative services consultants.
The figures show the bureaucracy's increasing spending on consultants has not been slowed by the Coalition government ascendancy to power.
Departments use consultants for jobs once done by public servants - from soil testing to investigating internal misconduct.
Public servants are concerned consultants will be used more because of a 16,500 person reduction in the bureaucracy's workforce.
At the start of 2014 the Education Department paid an external spin doctor $4000 a day that saw the consultant reap $95,000 for less than a month's work.